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The following parameters can be input for the sheathing applied to either or both sides of a shear wall in Wall Input View.
Sheathing Material
Shearwalls allows for Douglas-Fir plywood (DFP), Canadian softwood plywood (CSP), construction sheathing OSB, or Type X gypsum wallboard (GWB). OSB is manufactured in accordance with CSA Standard O325 and is not allowed when wet service conditions are selected in the Design Settings.
Shearwalls does not include diagonal lumber sheathing as specified in O86 10.3.4.
Changing the material refreshes the choices for all other inputs in the dialog.
Sheathing Thickness
The program provides a list of standard DFP, CSP, and OSB thicknesses taken from O86 tables 9.1-3, respectively. Standard GWB thicknesses of 1/2" and 5/8" are included. You can also enter a thickness yourself, but plywood and GWB are not manufactured in other thicknesses, so there is little need to enter a thickness other than one in the list.
The thickness is used to determine the depth of nail penetration for lateral nail strength for shear design and withdrawal strength for out-of-plane wind design.
Sheathing thickness can be also be "unknown", for which Shearwalls will determine the minimum allowable thickness that resists the applied load.
Changing the thickness refreshes the choices for nail size.
Note that for OSB, the thicknesses depend on the panel marking, and if this has been left "unknown", no thicknesses appear in the list until a panel marking is selected.
Orientation of long side of panel - For structural wood panels, this is vertical or horizontal. The orientation primarily affects wind component and cladding out-of-plane bending design, but there are certain exceptions for shear wall strengths that depend on orientation. For lumber siding, the orientation can also be diagonal or double-diagonal, and orientation affects shear strength.
Plies or Marking
The name of this field changes depending on the material selected; plies for plywood, panel marking for OSB. It affects the design strengths for from tables 9.3A-C, the resistance to out-of-plane wind loads, shear stiffness for deflection, and the panel bending component of shear wall strength.
OSB Panel Marking
For OSB, you must first select a panel marking in order to have choices for sheathing thickness and nail sizes. This marking corresponds to an equivalent panel thickness used in determining the shear strength (see O86 Table A9.2.2A).
Blocking
This check box indicates whether the sheathing panel edges on the selected side or sides are nailed to blocking. Note that vertically oriented panels are still considered to be unblocked unless they are staggered such that there are horizontal seams to be blocked.
An unblocked factor is applied to shear strength and deflection calculations for unblocked structural wood panels. Gypsum wallboard has different shear design values depending on whether it is blocked or unblocked.
Gypsum Wallboard Underlay
You can specify either 1/2" or 5/8" gypsum underlay beneath a wood structural panel. As per O86 11.4.3.1, there is no strength increase due to gypsum wallboard, in fact, unless longer nails are used to increase penetration, shear wall design strength using O86 11.6.2.2 will decrease. Gypsum underlay also affects the nail penetration for nail withdrawal design for out-of-plane wind loads. .